Distance enhancing golf tee

ABSTRACT

A new golf tee that increases the distance obtained on a drive is described. The tee increases driving distance by minimizing the energy absorbed by the tee when it is struck by the golf club. By absorbing less energy from the club head, the new tee minimizes the amount club head speed is reduced at impact, which translates into increased driving distance. The new tee also aids the golfer by providing a structure that allows the golfer to easily and consistently determine the amount the tee has been inserted into the ground.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims benefit of Provisional application serialNo. 60/213,923, filed on Jun. 26, 2000.

FIELD OF THE INVENTION

[0002] This invention relates to a golf tee.

BACKGROUND OF THE INVENTION

[0003] A traditional prior art golf tee is shown in FIG. 1. Golf teesare typically made from a single piece of wood. The geometry is easilyformed using readily available machining equipment, such as high-speedlathes. Tee 100 in FIG. 1 has shaft 10 that is tapered to a point at end20 to facilitate inserting end 20 into the ground. The top of shaft 10is flared out to a larger diameter. Top 30 of tee 100 is formed intocupped surface on which a golf ball can comfortably rest. The purpose ofa golf tee is to support a golf ball a short distance above the grounduntil contacted by the face of a golf club.

[0004] There are numerous variations of golf tees that can be found inthe prior art. Some of these purport to increase the distance obtained.Each of these prior art tees has numerous drawbacks that limit theirusefulness. The current invention overcomes these limitations.

[0005] Disco et al in U.S. Pat. Nos. 5,413,330 and 5,683,313, describeswhat is referred to as an improved hollow tee. The tee is marketed underthe name “Velocitee”, and the marketing literature states that the tee,“Provides the golfer with an uphill lie situation. This can produceoverspin which increases roll and distance.”

[0006] These tees are designed to be manufactured using injectionmolding techniques. They cannot be economically manufactured usingtraditional wood turning methods. As a result, they are considerablymore expensive than traditional wood tees. The tee of Disco has a largediameter hollow cylindrical shaft connected to a smaller diameter solidshaft with a point at one end for insertion into the ground. The hollowcylindrical shaft is sliced at an angle at the top where the golf ballrests. The tee is designed to be inserted at an angle into the ground,slanting towards the target, so that the top of the shaft (that was cutat an angle) rests parallel to the ground.

[0007] Unfortunately, the tee cannot function to promote overspin asintended. The spin imparted to the ball has solely to do with thetrajectory of the club head through impact. The tee does not alter thistrajectory, and therefore cannot affect spin. It is also interesting tonote that the body of the patent disclosure does not mention theproduction of overspin as an object of the invention, it is onlymentioned in the marketing literature. The only real benefit to thedesign that is mentioned in the patent disclosure of Disco is the use ofa vent, so that the hollow cylindrical shaft is not completely sealedwhen a golf ball is placed on the top of the shaft.

[0008] The vent supposedly keeps a vacuum from developing as the golfball first leaves the tee after being struck by the golf club. Noevidence is provided that such a vacuum would occur without the vent, orthat such a vacuum actually has an adverse impact on the ball flight. Astatement is made that incorporation of the vent will allow more of theclub momentum to be transferred to the ball (compared to use of a hollowshaft tee without such a vent), but no analysis is provided. It shouldbe noted that traditional tees would not require such a vent, if thevacuum described by Disco were in fact real, as there is no enclosed airspace underneath the ball when it is placed on top of a traditional tee.No direct claim is made in the patent disclosure of Disco that hisdesign provides for increased driving distance compared to traditionaltees.

[0009] The design of Disco also introduces a number of problems. Themethod used to insert the tee into the ground is different from thatused for traditional tees. The exact angle the tee is inserted needs tobe correctly judged by the golfer or the top of the tee will not beparallel to the ground and the ball may not be stable when set in place.There is no mechanism provided for the golfer to determine what thisangle is. The tee may need to be inserted into the ground numerous timesuntil the correct angle is obtained. Second, the tee must be rotated tothe correct point, or the surface where the ball is supposed to restwill be rotated away from being parallel to the ground. Third, the teeis visually quite different from existing tees. Any difference in whatthe golfer sees when standing over the ball, compared to what is seenusing traditional tees, can cause a problem. Because of the size of thetee and the required insertion angle, the golfer can see part of the teewhen standing over the ball. This is not desirable. Finally, there is nostraightforward mechanism to adjust and/or gauge the height of the ballabove the ground when using this tee. It is important for the golfer tobe able to consistently insert the tee so that the ball is the desiredheight above the ground. This can't be accomplished using this tee.Furthermore, different golfers will want to tee the ball differentheights above the ground. The fixed angle of the Disco tee does notallow the height to be altered easily.

[0010] Another tee marketed under the name “BoomBoyz” by SPLInternational, Inc. purports to increase driving distance. These teesare made using wood turning techniques similar to existing prior arttees. These tees have a slightly different shaft geometry than prior arttees. One section of the tee shaft is made thicker than normal. Themarketing literature states that the tee should first be inserted as farinto the ground as possible. Then it is pulled back up to the desiredheight, and rocked forward in the hole formed when it is inserted intothe ground. The intent is to have the tee in the ground, but not tightlyheld by the ground, so that it will provide less resistance whencontacted by the club head. This design may be able to affect drivingdistance to a degree. If the tee is not held tightly in the ground, itwill be more likely to come out of the ground when struck by the clubhead (as long as it does not break), and it will require less energy toaccomplish this than if the tee were held tightly.

[0011] Reducing the energy removed from the club head when it contactsthe tee, as intended in this second prior art tee, is also fundamentalto the functioning of the new tee described in following disclosure.However, the methods by which energy removed from the club head isreduced in the “BoomBoyz” tee and the tee of the current inventiondiffer substantially.

[0012] Reducing the energy removed from the club head by reducing thestability of the tee when placed in the ground, as implemented by the“BoomBoyz” tee, introduces a number of problems. First, when used asintended the top of this tee will not sit perpendicular to the ground,but will rest at an angle with respect to the ground. This makes it moredifficult to balance the golf ball on the top of the tee. Second, thetee will not be held firmly in place in the ground. It is thereforepossible for the tee to move after it has been inserted. This can changethe desired ball position and/or ball height after the golfer has setthe ball in place and is getting prepared to swing. Third, there is nomechanism provided that allows the golfer to gauge the height of the topof the tee above the ground after it has been inserted into the ground.Fourth, the “BoomBoyz” tee has a thicker shaft, which requires moreforce to insert into the ground than traditional tees do.

[0013] Finally, holding the tee in the ground less firmly does notguarantee that less energy will be absorbed by the tee when it isimpacted by the club head. It is still possible for the tee to be brokenwhen struck by the club head. (Breaking the tee constitutes theworst-case situation of energy absorption from the club head.) In fact,because the shaft of the “BoomBoyz” tee has been made thicker, a muchlarger input of energy is required before it would actually break. Ifthe “BoomBoyz” tee were firmly contacted by the club head, it isactually possible for it to absorb significantly more energy from theclub head than would a traditional tee, depending on how it iscontacted, how it is held in place, and the characteristics of theground. The method of insertion described in the marketing literature isnot sufficient to guarantee that the “BoomBoyz” tee would absorb lessenergy from the club head under all circumstances.

[0014] The new invention described below provides a tee that increasesdriving distance while overcoming all of the drawbacks of the prior arttees. The new tee reduces the energy removed from the club head when itcontacts the tee (which results in increased driving distance) byaltering the characteristics of the tee. The new tees can bemanufactured using existing turning (machining) techniques, andinherently provide a mechanism to gauge the height of the top of the teeabove the ground. The new tees remain stable when inserted into theground, and do not alter what is seen by the golfer when standing overthe ball. The new tees require the same amount of force to insert intothe ground as traditional wood tees.

OBJECTS OF THE INVENTION

[0015] It is an object of the current invention to provide a golf teethat achieves an increase in driving distance compared to prior arttees.

[0016] It is another object of this invention to provide a golf tee witha feature that allows a golfer to accurately and repeatably gauge theheight of the top of the tee above the ground when the golfer insertsthe tee into the ground.

[0017] It is another object of this invention to provide a tee thatincreases driving distance while requiring the same force to insert intothe ground as a conventional tee.

[0018] It is another object of this invention to provide a tee thatincreases driving distance while maintaining the same stability wheninserted into the ground as a conventional tee.

[0019] It is another object of this invention to provide a tee thatincreases driving distance that can be manufactured using anyconventional tee manufacturing process.

[0020] It is another object of this invention to provide a tee with allthe above benefits without increasing manufacturing cost compared toconventional tees.

SUMMARY OF THE INVENTION

[0021] Driving distance is determined by how much momentum istransferred from the golf club head to the golf ball at impact. In orderto maximize driving distance, this momentum transfer must be maximized.Significant research goes into the design of golf clubs to improve thistransfer. Energy transfer from the golf club to any structure or mediumother than the golf ball prior to the point the golf ball leaves theclub face, does not contribute to the momentum of the golf ball. The teeis one such structure.

[0022] It is common for a golfer to break the golf tee on a drive. Workis required in order to break (or permanently deform) the tee. The clubhead supplies the energy needed to accomplish this work. Even if the teedoes not break, the tee will be displaced and the ground around the teewill be permanently deformed. Work will still be done on the tee and theground. Again, the club head supplies the energy needed to perform thework done. In either case, the energy used to perform the work isremoved from the club head.

[0023] It has been determined that this energy is removed from the clubhead while it is still in contact with the golf ball. According to theUSGA (United States Golf Association), the typical contact time (theamount of time the golf ball is in contact with the club head) on anormal drive is approximately 0.45 msec. The club head will travel adistance of 0.8″ during that time (for an assumed club head velocity of100 mph). This distance is less than the distance between the bottom ofthe club head and the tee at the point of first impact of the ball withthe club head. The exact distance between the bottom of the club headand the tee at the point of first impact depends on the degree of loftof the clubface and the height of the club head above the ground duringthe swing. This distance has been calculated to be approximately 0.5″(assuming a driver with 10″ loft and a swing that brings the bottom ofthe club head 0.25″ below the top of the tee). Therefore, the club headwill strike the tee before the golf ball leaves the face of the club.Furthermore, the club head will travel approx. 0.3″ after it contactsthe tee. This is a sufficient distance to completely break the tee.

[0024] The removal of energy from the club head when it contacts the teereduces the club head velocity at the point of impact. The reducedvelocity shows up as a loss of momentum of the club head. Therefore,there is less momentum available to be transferred to the golf ball.This in turn reduces the maximum initial velocity of the golf ball as itleaves the club head. It is this initial velocity, in conjunction withlaunch angle (which is a function of the club head design and itsposition through impact) that primarily determine the distance the golfball flies.

[0025] The energy transferred from the golf club to the tee is no longeravailable to act on the golf ball. The result is reduced drivingdistance. The solution is to provide a tee that can adequately performthe function of holding the golf ball a desired distance above theground, while minimizing the energy transfer that occurs between theclub head and the tee.

[0026] A well-struck drive, with a club head speed of 100 mph (44.7 m/s)at the point of impact will fly approx. 275 yards. The typical driverhas a club head mass of approx. 200 g (0.2 kg). The momentum of the clubhead is then 8.94 kgm/s (M=mv, where M is momentum of the club head, mis the mass of the club head, and v is swing velocity). Measurementshave shown that the momentum absorbed by a typical wood tee when itbreaks is on the order of 0.2-0.4 kg m/s. Virtually all of this momentumwill be absorbed by the tee while the golf ball is still in contact withthe club head. Therefore, the club head momentum will decrease byapprox. 2.2-4.5% due to contact with the tee. This translates to atypical distance loss (due to energy transfer from the club head to thetee, and possibly the ground as well) of 6-12 yards (2.2-4.5% of 275yards). Driving distance can therefore be increased by as much as 6-12yards if the energy transferred to (or the momentum absorbed by) the teeand ground can be eliminated.

[0027] The reduction in distance due to use of conventional tees remainsapproximately constant regardless of swing velocity. High handicapgolfers with slower swing speeds will see approximately the sameimprovement in absolute driving distance as low handicap golfers withfaster swing speeds. As swing speed decreases, club head momentumdecreases. Therefore, the momentum transferred to the tee (which isapproximately fixed) represents a larger percentage of the total clubhead momentum. However, the total momentum of the club head is smaller,because the swing velocity is lower. The momentum absorbed by the tee isa larger percentage of a smaller quantity. The net effect is that theactual effect on absolute driving distance remains approximatelyconstant over a wide range of variation in swing velocity.

[0028] Use of other types of tees designed for increased durability mayin fact have a larger detrimental effect on driving distance. Some ofthese tees will not break when struck by the club head. When such a teeis used in a tee box with hard ground, significantly more energy may beremoved from the club head in displacing the tee and deforming theground. Increasing the durability of tees, of which there are many priorart examples (tees with larger than normal shaft diameters, tees madeout of hard polymer materials, etc.), will adversely affect drivingdistance.

[0029] The current invention minimizes the amount of energy removed fromthe golf club head when it contacts the tee during the swing by reducingthe strength of the tee shaft (compared to traditional tees) to forcesapplied perpendicular to the shaft. In the preferred embodiments, thereduction in shaft strength is accomplished over a first section of theshaft. The remaining portion of the shaft is kept at the traditional teeshaft strength. It should be understood that the invention is notlimited in any way to the strength of this remaining portion of theshaft. The reduction of shaft strength results in a tee that breaks witha much lower applied force than required by traditional tees. Byreducing the strength of the tee shaft, the tee will break with lessenergy input from the club head. Therefore, more energy is available tobe transferred to the golf ball, which will increase the distance thegolf ball travels.

[0030] The fundamental idea on which the invention is based is that thenew tees are designed to break when used. That is, the new tees aredesigned to be single use. This is contrary to conventional thought withregard to tees, where if anything there has been a desire to make teeslast longer by increasing their strength. The invention here realizesthat if the cost of the tee can be kept small, the increased distanceachieved will outweigh the increased costs associated with a single usetee (the tees themselves do not cost more, but more tees will be usedper round of golf).

[0031] The new tee design only reduces the strength of the tee over asection of the shaft length. The rest of the shaft has characteristicssimilar to traditional tees. This is done so that the new tee requiresapproximately the same force to insert into the ground as a traditionaltee. Also, the stability of the new tees when inserted in the groundwill be similar to traditional tees.

[0032] The preferred embodiments reduce shaft strength over a section ofshaft length by forming a feature that acts as a stress concentrator.The stress concentrator focuses energy input to the tee from the clubhead at the point of reduced shaft strength, rather than distributingthe input energy along the entire shaft length as occurs in traditionaltees. This acts to further reduce the perpendicular input force neededto break the tee, which in turn further reduces the energy (or momentum)absorbed by the tee. The stress concentrator is located at a point alongthe shaft where it will be approximately flush with the ground when thetee is inserted into the ground by the golfer. This forms a moment armbetween the top of the tee (where the club is most likely to contact thetee due to its shape which flares at the top) and the location of thestress concentrator. This moment arm also acts to reduce the input forcerequired to break the tee.

[0033] The addition of a stress concentrator feature does notsignificantly impact the compression load the new tee can withstand. Thenew tee has the same resistance to breaking as a traditional tee wheninserted into the ground by a golfer (force is applied parallel to theshaft axis), but it will break with significantly less energy input fromthe club head compared to a traditional tee when impactedperpendicularly by the club head.

[0034] It should be noted that it is also possible to reduce thestrength of a tee shaft over its entire length (which would typically bedone by reducing the shaft diameter). This approach, however, has thedrawback that the portion of the shaft inserted into the ground has nowhas a reduced diameter. The stability of a smaller diameter tee wheninserted into the ground (especially if the ground is soft) will besignificantly reduced. Such a tee could change position after beinginserted in the ground, which would adversely affect the drive.

[0035] The above design also does not have a stress concentratorfeature, and will therefore still absorb more input energy before itbreaks than will the preferred embodiment. The energy input from theclub head will be distributed along the entire exposed shaft length,rather than being concentrated at a particular point along the shaft (asoccurs in the preferred embodiment). For a fixed amount of input energy,the stress present at any point along the shaft of a reduced shaftdiameter tee will be less than the stress present at the location of thestress concentrator in the preferred embodiment (for the case where theshaft diameter at the location of the stress concentrator is the same asthe shaft diameter of the reduced diameter tee). It can be seen that itwill take more energy to break a tee without a stress concentratorfeature than it will take to break a tee with a stress concentratorfeature, and that the use of a stress concentrator feature also allowsthe new tee to have improved in-ground stability.

[0036] It should be noted that there is no restriction on the diameterof the tee shaft of the present invention. A stress concentrator featurecan be added to a tee with any desired shaft diameter. The preferredembodiments keep the nominal shaft diameter approximately the same asthat used in traditional prior art tees, but this is not required.

[0037] There is another function of the portion of the shaft withreduced strength (or the stress concentrator feature). Having a stressconcentrator feature provides a visual reference point for determininghow far the tee has been inserted into the ground. A tee with reduceddiameter over its entire shaft length does not provide such a referencepoint. This reference point can be used to judge the height of the topof the tee above the ground. Use of this reference allows the golfer torepeatably tee his ball a consistent height above the ground.

[0038] Yet another benefit is related to reducing the energy absorbed bythe tee. When the golf club head contacts the tee, it applies a force tothe tee. At the same time, an equal and opposite force is applied to theclub head by the tee. This force, in addition to reducing club headvelocity, is also capable of altering the position of the club headthrough impact. Depending on the trajectory, the club head can be causedto rotate slightly in one or more axes when it contacts the tee. Thisoccurs while the clubface is still in contact with the golf ball. Therotations applied to the club head can impart unwanted spins to the golfball. These spins can potentially accentuate hooks or slices. Byminimizing the force needed to break the tee, as is done in the currentinvention, the reaction forces exerted by the tee on the club head arealso minimized. Any detrimental effects on club head trajectory due tocontact with the tee will therefore also be minimized.

[0039] Finally, it is possible to manufacture a tee with a stressconcentrator feature (a tee with reduced strength over only a section ofits shaft) using exactly the same processes used to manufactureconventional tees. No secondary operations are required, and noprocessing throughput time penalty or cost increases will be incurred.The feature can easily be made using the wood turning techniquescurrently used to make traditional tees. Turning methods could also beused to make tees out of other materials (such as extruded plastic rod),if desired. The new tees can also be made using molding techniques,where the stress concentrator feature is incorporated directly into themold cavity used to form the tee. The features and benefits of the newtees (compared conventional tees) are provided without any cost penalty.

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Other objects, features and advantages will occur to thoseskilled in the art from the following description of the preferredembodiments and the accompanying drawings in which:

[0041]FIG. 1 shows a two dimensional (2D) cross sectional view of atypical prior art golf tee.

[0042]FIG. 2A shows a 2D cross sectional view of the preferredembodiment of the new distance enhancing golf tee with a notch in theshaft that acts as a stress concentrator and tee height indicator.

[0043]FIG. 2B shows a 2D cross sectional view of the preferredembodiment of the new distance enhancing golf tee with a radiussednotch.

[0044]FIG. 3 shows a 2D cross sectional view of an alternate embodimentof the new distance enhancing golf tee with two separate stressconcentration regions.

[0045]FIG. 4 shows a 2D cross sectional view of an alternate embodimentof the new distance enhancing golf tee.

[0046]FIG. 5 shows a 2D cross sectional view of an alternate embodimentof the new distance enhancing golf tee.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0047] A stress concentrator feature on the shaft of a golf tee can bedefined as an area of the tee shaft where the shaft strength has a localminimum. That is, on either side of the location of the stressconcentrator feature on the shaft, the strength of the shaft is greaterthan the strength of the shaft at the location of the stressconcentrator feature.

[0048] In the preferred embodiment, the shaft strength is reduced over arelatively small section of the shaft length. The most straightforwardmethod to reduce shaft strength is to reduce the shaft diameter. Thepreferred embodiment has a small section of shaft with reduced diameter,which in effect forms a notch in the shaft. The notch acts as a stressconcentrator, which focuses the energy input from the club head to thelocation of the stress concentrator feature.

[0049] In order to act reasonably as a stress concentrator, the diameter(or thickness) of the tee shaft at the location of the local minimumshould be at least 10% smaller than the nominal diameter of the shaft inthe local region around the stress concentrator. The preferredembodiments have a local minimum in the shaft diameter that is 40%smaller than the nominal shaft diameter. However, it should be notedthat there is no limitation on the required percentage difference inshaft diameter at the local minimum compared to the nominal shaftdiameter. Different ratios may be desirable for different nominal teeshaft diameters or with tees made of different materials.

[0050] Most of the discussion here focuses on tees made of wood, whichare made on high-speed lathes. This manufacturing process results intees that have a cylindrical geometry, and are circularly symmetric. Theinvention is not however limited to such geometries. A stressconcentrator feature could be added to a tee with a shaft that had asquare or rectangular cross section, for example. Such a tee could bemade using a different manufacturing process, such as injection moldingof a polymer material.

[0051] A stress concentrator feature also does not need to extend aroundthe entire perimeter of the tee shaft. An effective stress concentratorfeature could exist on only one side of a tee shaft, or on oppositesides of the shaft (or extend over only a portion of the circumferenceof a round shaft). For example, a second operation could be added wherea traditional tee is placed in a press to form notches on opposite sidesof the tee shaft. Drilling a small hole, either partially or completelythrough the tee shaft, can also create a stress concentrator feature.Such a hole would weaken the shaft at the location of the hole.

[0052] The invention is not limited in any way in the materials used toform the tee, the geometry of the tee shaft (cross section shape orthickness), or the geometry of the stress concentrator feature and theextent to which it extends around the perimeter of or through the teeshaft. All that is required is a feature that creates a local minimum inthe strength of the tee shaft.

[0053] A tee with a stress concentrator (formed by a notch) in the shaftis straightforward to manufacture. Since traditional wood tees aresimple turnings, changing the diameter over a section of the shaft canbe accomplished by changing the geometry of the tool used to make theturning. There is no increase in manufacturing time or cost required toaccomplish this. No secondary operations are needed to form the stressconcentrator in the shaft. A stress concentrator feature can also easilybe incorporated in the tooling for a molded tee without affecting thecost of the part. No increase in material costs or machine cycle timeswould be needed. FIG. 2A shows a cross section of the preferredembodiment of the new tee design. Tee 200 is similar to prior art tee100 shown in FIG. 1, except for stress concentrator 40 in shaft 1. Holesor other geometries that can form stress concentrators can beaccomplished without additional costs when certain manufacturing methodsare used (holes can be done easily in injection molding, for example) orwith slight cost increases using secondary operations (such as drillinga hole in a formed tee). Tee 500 in FIG. 5 shows hole 80 drilled throughthe shaft 10 of tee 500, where hole 80 forms a local minimum inperpendicular shaft strength at the location of the hole.

[0054] In use, the new golf tee 200 is inserted into the ground untilthe portion of shaft 10 with reduced strength (stress concentratorfeature 40) is approximately flush with the ground. When the club headcontacts the golf ball and tee 200, shaft 10 of tee 200 will break atthe location of stress concentrator feature 40. Furthermore, by locatingthis point flush with the ground, the moment arm that is formed betweenthe location where the club head impacts top 30 of tee 200 and thestress concentrator feature 40 maximizes the force applied at stressconcentrator feature 40, for a fixed energy input from the club head.When the club head applies a force to the top of tee 200 perpendicularto the axis of tee shaft 10, tee shaft 10 will break with a much smallerapplied force than would a traditional tee. The accompanying reductionin club head velocity that occurs when the tee 200 breaks will besignificantly less than the reduction that occurs when a traditional teeis used.

[0055] In order for tee 200 to function properly, the club head mustcontact tee 200 somewhere between the location of the stressconcentrator 40 and the top of tee 30. If the club head contacts tee 200between the location of stress concentrator 40 and the ground, then tee200 will break along shaft 10 below stress concentrator 40, and the teewill absorb the same energy (or momentum) as a traditional tee. This isthe reason why the preferred embodiment locates stress concentrator 40 adistance below the top of tee 30 so that stress concentrator 40 will beapproximately flush with the ground when top of tee 30 is the desiredheight above the ground. Note that it is also possible to insert tee 200farther into the ground (so that stress concentrator 40 is slightlybelow the surface of the ground) and still have it function correctly.The amount stress concentrator 40 can be pushed past the ground surfaceand still have the tee function correctly depends primarily on thecharacteristics of the ground. The softer the ground, the farther tee200 can be inserted and still work effectively.

[0056] Tee 200 retains sufficient strength to resist breaking when aforce is applied to top 30 of tee 200, parallel to the tee shaft 10axis. This is required in order to be able to insert the tee into theground. It has been determined that the diameter of traditional teesprovides a column that can withstand much greater compression loadingthan is needed in order to insert a tee into the ground. Reducing thediameter of a portion of the shaft as required by the current inventioncan therefore be done while still maintaining sufficient strength towithstand the compression loads typically encountered.

[0057] The preferred embodiment locally reduces the diameter of shaft 10of tee 200 by approximately 40% to form the stress concentrator feature40. Shaft 10 of tee 200 in the preferred embodiment has a nominaldiameter of 0.19″, and the diameter at the location of the stressconcentrator feature 40 reduces to 0.11″. Note that the invention is notin any way limited to these dimensions. The invention only requires thatthere be a section of the shaft with a locally reduced strength comparedto the rest of the shaft.

[0058] Stress concentrator 40 in shaft 10 of FIG. 2A is shown with sharpcorners. Sharp corners increase the stress concentration that occurs, byreducing the area over which the input force is distributed. It may bedesirable to reduce the amount of stress concentration for a given shaftstrength (a given diameter or thickness) to improve the manufacturingyields of the device. The radiuses of the edges of stress concentrator40 determine the areas over which stress is concentrated. A very smallradius results in very high levels of local stress, and could adverselyimpact manufacturability of the device. A slight increase in the radiuscan be used if desired to accomplish a reduction in stress concentrationfor a given reduction in shaft strength.

[0059] Tee 201 is shown in FIG. 2B with a radiused stress concentrator.Joint 41 of stress concentrator 40 is the most critical to radius toreduce stress concentration if needed for manufacturability. Thepreferred embodiment uses a radius of 0.015″ for joint 41 of stressconcentrator 40. It should be noted that the invention is not limited tothe use of any particular radius. The depth of the notch and thedimension of the radius in joint 41 can both be varied to achievedifferent mechanical characteristics. The invention is not limited inany way in the combination of shaft diameter and stress concentratorradius used.

[0060] Stress concentrator 40 in shaft 10 (of tees 200 and 201) shouldbe located a distance below top of tee 30 so that top of tee 30 is thedesired height above the ground when the tee is inserted in the ground(to the point where stress concentrator 40 is approximately flush withthe ground). The preferred embodiments locate stress concentrator 40approximately 1.0″ below top 30, which is a desirable distance for usewith a typical driver. It should be understood however that theinvention is not in any way limited to this dimension. In fact, thepreferred distance between stress concentrator 40 and top 30 will besmaller for a tee shot with an iron club (or a fairway wood) than a teeshot with a driver. In the case of a tee shot with an iron club, stressconcentrator 40 will preferably be located approximately 0.30″ below topof tee 30. Again, it should be noted that the invention is not in anyway limited to locating the stress concentrator at any of theabove-identified distances away from the top of the tee. The use ofdistances other than those identified above will still result in a teewith reduced momentum absorption compared to traditional tees.

[0061] It is also possible to construct a tee with more than one sectionof the shaft with reduced strength (or more than one stress concentratorfeature). The invention is not limited in the number of stressconcentrators contained in the shaft. An example embodiment is shown inFIG. 3, where tee 300 contains two stress concentrators in shaft 10.Stress concentrator 40 in shaft 10 of tee 300 is located a distance fromtop 30 of tee 300 selected to be optimum when a driver is used for a teeshot, and stress concentrator 50 in shaft 10 of tee 300 is located adistance from top 30 of tee 300 selected to be optimum when an iron isused for a tee shot.

[0062] Tee 400 in FIG. 4 shows another alternative embodiment of the newinvention. The nominal diameter of shaft 10 on either side of stressconcentrator feature 40 is no longer the same, as was shown in FIGS. 2A,2B, and 3. The nominal diameter of shaft section 70, which is thesection between top 30 and stress concentrator feature 40 of tee 400 issmaller than the nominal diameter of shaft section 60, which is thesection between tip 20 and stress concentrator feature 40 of tee 400.There is still a local minimum shown in the shaft diameter that formsstress concentrator 40.

[0063] This alternative embodiment allows the stress concentratorfeature to continue to function, regardless of the depth tee 400 isinserted into the ground. Tee 400 can now be inserted into the groundpast the point where stress concentrator 40 would be flush with thesurface of the ground, yet still function as intended. Only section 60of tee shaft 10 will be held in place by the ground. Since section 60has a larger diameter than section 70, section 70 will not be heldfirmly in place by the ground, even if tee 400 is inserted so thatstress concentrator 40 is located a significant distance below theground surface. Input force will still be concentrated at stressconcentrator 40, and the tee will still break at this point. This designcan effectively be used for a driver or an iron shot without the needfor multiple tees with different distances between the top of the teeand the location of the stress concentrator, or tees with multiplestress concentrators. This design does not require the tee to be fullyinserted, pulled out to a desired height and then rocked forward asrequired by one prior art tee. Tee 400 will be held firmly in place inthe ground while still providing its driving distance improvement.

[0064] The preferred embodiment shown in FIG. 4 uses a diameter forshaft section 60 of 0.20″, a diameter of 0.15″ for section 70, and adiameter at joint 41 of stress concentrator 40 of 0.1″. Stressconcentrator 40 is located 1.0″ from the top of the tee (the same as thedistance identified earlier for tees 200 and 201, for use with adriver). It should be noted that this embodiment is not limited in anyway in the diameters (or thickness) used for the various shaft sections,or in the location of stress concentrator 40. The dimensions given hereare representative, and have been shown to work well. They are not theonly dimensions that will work, and the invention should not beconstrued to be in any way limited to use of only these dimensions. Thekey elements of this embodiment are: 1) use of a stress concentratorfeature located at a point along the shaft of a tee, and 2) a firstsection of the tee shaft below the stress concentrator feature that hasa first diameter or thickness, a second section of the tee shaft abovethe location of the stress concentration feature that has a seconddiameter or thickness, where the diameter or thickness of this secondsection of tee shaft is less than (or equal to, as described in previousembodiments) the diameter or thickness of the first section of teeshaft.

[0065] Other embodiments will occur to those skilled in the art and arewithin the following claims:

[0066] What is claimed is:

1. A golf tee providing increased driving distance compared toconventional tees and further including a method to judge the height ofthe top of the tee above the ground, said golf tee comprising: A shaftwith two ends and a first nominal diameter over at least a portion ofthe shaft length, where said shaft possesses a strength to resistbreakage from perpendicularly applied forces, A tip located at the firstend of said shaft formed into a point for insertion into the ground, Atop located at the second end of said shaft, where said top is flaredout to a second diameter or thickness larger than said first diameter orthickness, wherein said top further is preferably formed into a cuppedshape to hold a golf ball in place, and A stress concentrator located ata point along the shaft between the first and second ends of said shaft,wherein said stress concentrator reduces the strength of said shaft toperpendicularly applied forces.
 2. The tee of claim 1 wherein saidstress concentrator is formed by modifying said shaft to contain a localminimum in the shaft diameter or thickness, at the location of saidstress concentrator feature.
 3. The tee of claim 2 where said stressconcentrator is accomplished by forming a notch that extendscircumferentially around at least a portion of said shaft.
 4. The tee ofclaim 3 where said notch is radiussed.
 5. The tee of claim 2 where saidstress concentrator is accomplished by forming a hole that at leastpartially penetrates said shaft.
 6. A golf tee providing increaseddriving distance compared to conventional tees and further including amethod to judge the height of the top of the tee above the ground, saidgolf tee comprising: A shaft with two ends and a first nominal diameterover at least a portion of the shaft length, where said shaft possessesa strength to resist breakage from perpendicularly applied forces, A tiplocated at the first end of said shaft formed into a point for insertioninto the ground, A top located at the second end of said shaft, whereinsaid top is flared out to a second diameter or thickness that is largerthan said first diameter or thickness, wherein said top is preferablyformed into a cupped shape to hold a golf ball in place, and Multiplestress concentrators located at various points along said shaft betweenthe first and second ends, where said stress concentrators reduce thestrength of said shaft to perpendicularly applied forces.
 7. The tee ofclaim 6 wherein said stress concentrators are formed by modifying saidshaft to contain local minima in the shaft diameter or thickness, at thelocations of said stress concentrators.
 8. The tee of claim 7 where thestress concentrators are accomplished by forming notches that extendcircumferentially around at least a portion of said shaft.
 9. The tee ofclaim 8 where said notches are radiussed.
 10. The tee of claim 6 wheresaid stress concentrators are accomplished by forming holes that atleast partially penetrate said shaft.
 11. A golf tee providing increaseddriving distance compared to conventional tees and further including amethod to judge the height of the top of the tee above the ground, saidgolf tee comprising: A shaft with two ends, where said shaft is dividedinto two separate sections with the transition between the two sectionslocated at a first fixed point, the first shaft section comprising theportion of said shaft between the first end and said fixed point, thesecond shaft section comprising the portion of said shaft between thesecond end and said fixed point, where said first section has a firstnominal diameter or thickness and said second section has a secondnominal diameter or thickness less than or equal to said first sectionnominal diameter or thickness, A tip located at the first end of saidshaft formed into a point for insertion into the ground, A top locatedat the second end of said shaft, wherein said top is flared out to athird diameter or thickness that is larger than said first or seconddiameter or thickness, wherein said top is preferably formed into acupped shape to hold a golf ball in place, and A stress concentratorfeature located at said fixed point along said shaft between said firstand second shaft sections, where said stress concentrator reduces thestrength of said shaft to perpendicularly applied forces.
 12. The tee ofclaim 11 where said stress concentrator is formed by modifying saidshaft to contain a local minimum in the shaft diameter or thickness, atthe location of said stress concentrator.
 13. The tee of claim 12 wherethe stress concentrator is accomplished by forming a notch that extendscircumferentially around at least a portion of said shaft.
 14. The teeof claim 13 where said notch is radiussed.
 15. The tee of claim 11 wheresaid stress concentrator is accomplished by forming a hole that at leastpartially penetrates said shaft.